Wellhead assembly quick install

ABSTRACT

A wellhead assembly uses a plurality of pins to secure a casing head to a mandrel during installation. The mandrel is installed onto a casing string with the casing head is positioned on the mandrel so as to align a plurality of through-holes with a groove encircling the mandrel. The plurality of pins are inserted through the through-holes and into the groove of the mandrel, locking the casing head onto the mandrel so drilling can occur. Installation and tear down are faster and less labor intensive.

PRIORITY CLAIM AND CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Application No. 62/407,445 filed Oct. 12, 2016 and titled “CASING HEAD ASSEMBLY.” The content of the above-identified patent document is hereby incorporated by reference.

TECHNICAL FIELD

The present application relates generally to a wellhead assembly and more particularly to a wellhead assembly using pins with a mandrel for installation and disassembly.

BACKGROUND

Well installs and tear downs are necessary steps for the production of oil and gas. In addition to the incredible forces involved during the production of oil and gas, the coupling of different components requires sealing to prevent leakage of the produced fluids and also the strength to handle the forces of the produced fluids, which sometimes exceed more than 10,000 pounds per square inch (psi). Typical conventional coupling of wellhead assemblies requires a significant amount of welding, that could add four to ten hours of labor to each installation or tear-down. Other proposed wellhead assemblies, such as that proposed in U.S. Pat. No. 9,593,549, are coupled using a locking collar coupled to the mandrel, but these solutions do not yield a perfect seal on the wellhead assembly due to the multiple portions of the locking collar. In addition, damage to any segment of the locking collar results in a failed seal, which delays the production of fluids until the locking collar is repaired or replaced.

There is, therefore, a need in the art for an improved wellhead assembly.

SUMMARY OF THE DISCLOSURE

The present application relates generally to a wellhead assembly and more particularly to a wellhead assembly using pins with a mandrel to install it.

In a first embodiment, a wellhead assembly is provided. The wellhead assembly includes a casing head, a mandrel, and a plurality of load-bearing pins. The casing head is coupled to a casing string. The mandrel inserts into the casing head. The plurality of load-bearing pins secures the casing head onto the mandrel.

In a second embodiment, a system is provided. The system includes a casing string and a wellhead assembly. The wellhead assembly includes a casing head, a mandrel, and a plurality of load-bearing pins. The casing head is coupled to a casing string. The mandrel inserts into the casing head. The plurality of load-bearing pins secures the casing head onto the mandrel.

In a third embodiment, a method is provided. The method includes coupling a casing head to a casing string; inserting a mandrel into the casing head; and securing the casing head onto the mandrel via a plurality of load-bearing pins.

Additional features and advantages of the present disclosure are described in, and will be apparent from, the following Detailed Description of the Invention and the Figures.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present disclosure and its advantages, reference is now made to the following description taken in conjunction with the accompanying drawings, in which like reference numerals represent like parts:

FIG. 1 illustrates a wellhead assembly according to various embodiments of the present disclosure;

FIG. 2 illustrates a modified wellhead assembly with a plurality of load bearing pins according to various embodiments of the present disclosure;

FIG. 3 illustrates a casing head according to various embodiments of the present disclosure;

FIG. 4 illustrates a mandrel according to various embodiments of the present disclosure;

FIG. 5 illustrates a load-bearing pin according to various embodiments of the present disclosure;

FIG. 6 illustrates an example process of assembling a wellhead assembly according to various embodiments of the present disclosure; and

FIG. 7 illustrates an example process of disassembling a wellhead assembly according to various embodiments of the present disclosure.

DETAILED DESCRIPTION

FIGS. 1 through 7, discussed below, and the various embodiments used to describe the principles of the present disclosure are by way of illustration only and should not be construed in any way to limit the scope of the invention. Those skilled in the art will understand that these principles may be implemented in any type of suitably arranged device or system.

FIG. 1 illustrates a wellhead assembly 100 according to various embodiments of the present disclosure. The embodiment of the wellhead assembly 100 illustrated in FIG. 1 is for illustration only. FIG. 1 does not limit the scope of this disclosure to any particular implementation of an oil or gas well.

The wellhead assembly 100 includes a casing head 110, a casing string 115, and a blowout preventer (BOP) 120. The casing head 110 is positioned over the casing string 115. The BOP 120 is coupled to the top of the casing head 110. The wellhead assembly 100 contains pressure through an interface with the BOP 120, allows drilling and casing strings to be installed, allows for sealing to be made outside each casing string to seal off an annulus, and provides access to each intermediate casing string and the production casing string.

In a wellhead assembly, the casing head 110 must be secured onto the casing string 115. Once the well begins producing, a significant force is introduced from rising oil and/or gas. If the casing head 110 is not secured to the casing string 115, the force from the oil and/or gas production would cause the casing head 110 to disengage from the casing string 115, potentially causing significant damage to the drilling rig or workers present. In extreme cases, for example ocean production, not securing the casing head 110 could cause an oil spill. In certain embodiments the casing head 110 may be secured to the casing string 115 by welding both the inside and outside of where the casing head 110 and casing string 115 come together. However, this method is very time costly. In other embodiments, the casing head 110 is secured to the casing string 115 by incorporating a mandrel 210 with a securing ring in grooves located between the mandrel 210 and the casing head 110. The mandrel 210 is described in further detail below.

Although shown in FIG. 1 with a single blowout preventer, the BOP 120 may also represent a blowout preventer system or blowout preventer stack. One of ordinary skill in the art will understand that the components of the BOP 120 will vary depending on the type of well in which the wellhead assembly 100 is being used. For example, the specific BOP 120 will vary based on whether the wellhead assembly 100 is being used on a land well, offshore rig, and/or subsea well. The BOP 120 referenced herein may refer to any suitable BOP 120 system known in the art.

Although FIG. 1 illustrates one example of a wellhead assembly 100, various changes may be made to FIG. 1. For example, the components of the wellhead assembly 100 are for illustration only. Various components in FIG. 1 could be omitted, combined, or further subdivided and additional components could be added according to particular needs.

FIG. 2 illustrates a modified wellhead assembly 200 with a plurality of radial load-bearing pins 215 according to various embodiments of the present disclosure. The embodiment of the modified wellhead assembly 200 illustrated in FIG. 2 is for illustration only. FIG. 2 does not limit the scope of this disclosure to any particular implementation of an oil or gas well.

The modified wellhead assembly 200 includes a casing head 205, a landing mandrel 210 and a plurality of load-bearing pins 215. The casing head 205 includes a plurality of through holes 220. The through holes 220 can be threaded or smooth. The landing mandrel is coupled to the casing string 115 to be used in the production of oil and gas. The landing mandrel 210 includes a plurality of grooves 225. The groove 225 is smooth and runs for the circumference of the landing mandrel 210. Although referenced in this disclosure as a landing mandrel, one of ordinary skill in the art will understand that such a component may be referenced as several different names, including but not limited to a connector, casing mandrel, landing mandrel, and/or crossover mandrel. The name used herein is exemplary and not limiting.

The casing head 205 installs onto the landing mandrel 210. The outer profile of the landing mandrel 210 mates with the inner profile of the casing head 205 to position the landing mandrel 210. The casing head 205 is aligned for access to different ports located on the outside structure of the casing head 205. The size and weight of the casing head 205 requires significant initial alignment, meaning that adjusting the casing head 205 once placed is difficult. The profiles of both the interior of the casing head 205 and the exterior of the landing mandrel 210 are structured with an upper diameter less than a lower diameter. The transition between the two diameters can be gradual or use a step 230. The mating of the casing head 205 and the landing mandrel 210 aligns the through-hole 220 with the groove 225. A load-bearing pin 215 is inserted in the through-hole 220 and into the groove 225. The through-hole 220 can be oriented at a downward angle to increase the force of the pins and also reduce the slip due to the vibration of producing fluids. The through holes 220 can alternate being angled downward and perpendicular to the fluid flow. Although described here as a pin, one of ordinary skill in the art will understand that such a component may be referenced as several different names, including but not limited to a bolt, screw, dowel and/or rod. The name used herein is exemplary and not limiting.

The significant forces experience by the casing head 205 during production of oil and gas determines how many load-bearing pins 215 are required to secure the casing head 205 onto the landing mandrel 210. The plurality of load-bearing pins 215 (e.g., twelve, evenly distributed around the circumference) is determined based on the shear force for each. The strength of the load-bearing pins 215 is determined by the tensile strength of the property class and the thickness or diameter of the body. The depth of the groove 225 is determined based on the rotational force exerted on the load-bearing pins 215. The use of load-bearing pins 215 in lieu of a collar encircling the entire circumference of circumference of the landing mandrel 210 is not a self-evident substitution, due to the very large forces involved. Mechanically, concerns regarding shearing of the load-bearing pins 215 and/or localized deformation of the landing mandrel 210 and/or the casing head 205 logically militate against using load-bearing pins 215 instead of a collar distributing the forces around the entire circumference of the landing mandrel 210 and the casing head 205. However, the shape of the mating interface between the landing mandrel 210 and the casing head 205, combined with the number of load-bearing pins 215 and appropriate selection of materials, provides sufficient strength to avoid shearing or significant deformation. Those skilled in the art will understand how to select, with no more experimentation and testing beyond that ordinarily required for designs of the type described herein, appropriate materials and the number of load-bearing pins, given the mating interface depicted and described. For example, the material comprising the load bearing pins 215 may be zinc, copper, and/or steel, or any other appropriate material determined by one skilled in the art.

The load-bearing pins 215 can be partially or fully threaded. In some embodiments, the front end 505 of the load-bearing pin 215 is smooth for entering the groove 225. In this embodiment, wherein he load-bearing pins 215 can be smooth, the load-bearing pins 215 can be held in place by different means, such as magnetic or friction. The back end 515 of the load-bearing pins 215 can be shaped to mate with a tool for rotating, such as a drill, a wrench, or a screwdriver. Although not visible in FIG. 2, the front end 505 and back end 515 of load-bearing pins 215 are discussed in greater detail below.

In certain embodiments, the load-bearing pins 215 are permanently installed in the casing head 205. The load-bearing pins 215 can include a wider front portion and back portion in order to not allow the load-bearing pin 215 to be removed.

In certain embodiments, the load-bearing pins 215 can be functionally in the extended state, such as by use of springs or magnets on the inside of the casing head 205 around the through hole. In this embodiment, the back end of load-bearing pins 215 are functional to pull the load-bearing pin 215 with a stopper to keep the front end retracted.

In certain embodiments, the load-bearing pins 215 may include a first flange 520 at the front end 505 that act as a locking mechanism when rotated in a channel at the back end of the groove. In certain embodiments, the load-bearing pins 215 may also include a second flange 525 located in a middle portion 510 that extend into a horizontal channel 320 of the through hole 220. When the load-bearing pin 215 is fully inserted into the groove 225, the flanges line up with a quarter-circumferential channel to orient the load-bearing pin 215 correctly with the groove channel. Although not visible in FIG. 2, the first flange 520, the second flange 525 and the horizontal channel 320 are discussed in greater detail below.

Although FIG. 2 illustrates one example of a modified wellhead assembly 200, various changes may be made to FIG. 2. For example, the components of the modified wellhead assembly 200 are for illustration only. Various components in FIG. 2 could be omitted, combined, or further subdivided and additional components could be added according to particular needs.

FIG. 3 illustrates a casing head 300 according to various embodiments of the present disclosure. The embodiment of the casing head 300 illustrated in FIG. 3 is for illustration only. FIG. 3 does not limit the scope of this disclosure to any particular implementation of a wellhead assembly.

The casing head 300 includes a first inner diameter 305, a second inner diameter 310, a plurality of through holes 315, a horizontal channel 320, and a quarter-circumferential channel 325. The casing head 300 connects to a BOP 120 by welding, threading or bolting at the top of the casing head 300. The casing head 300 is structured with an inner diameter profile that a first inner diameter 305 is greater at the bottom than a second inner diameter 310 at the top.

The casing head 300 includes the plurality of through holes 315. The through holes 315 align the load-bearing pins 215 with the grooves 225 in the landing mandrel 210. The through holes 315 can include the horizontal channel 320 and the quarter-circumferential channel 325. The horizontal channel 320 is used in embodiments where the load-bearing pins 215 include one or more flanges. The horizontal channel 320 guides the first flange 520 located at the front of the load-bearing pin 215 to the groove 225 in the landing mandrel 210. The quarter-circumferential channel 325 is located at a distance to align with the second flange 525 in the middle portion of the load-bearing pin 215 once the load-bearing pin 215 is fully inserted. When the load-bearing pin 215 is rotated, the second flange 525 limits the rotation of the load-bearing pin 215 in a manner that the first flange 520 enters a channel located at the inside of the groove 225 in the landing mandrel 210. While the quarter-circumferential channel 325 is illustrated on the top side of the horizontal channel 320, in certain embodiments the quarter-circumferential channel 325 could be located on the bottom side of the horizontal channel 320. Locating the quarter-circumferential channel 325 on the bottom side of the horizontal channel 320 would avoid any forces such as vibrations from causing the load-bearing pin 215 to rotate backwards. In another embodiment, a notch could be created at the top of the quarter-circumferential channel 325 to lock the load-bearing pin 215 from rotating due to forces such as vibrations.

Although FIG. 3 illustrates one example of a casing head 300, various changes may be made to FIG. 3. For example, the components of the casing head 300 are for illustration only. Various components in FIG. 3 could be omitted, combined, or further subdivided and additional components could be added according to particular needs.

FIG. 4 illustrates a landing mandrel 400 according to various embodiments of the present disclosure. The embodiment of the landing mandrel 400 illustrated in FIG. 4 is for illustration only. In certain embodiments, the landing mandrel 400 is the landing mandrel 210 shown in FIG. 2. FIG. 4 does not limit the scope of this disclosure to any particular implementation of a wellhead assembly.

The landing mandrel includes a first outer diameter 405, a second outer diameter 410, a step 415, a groove 420, and a channel 425. In certain embodiments, the transition between the two diameters 405 and 410 can be gradual. In another embodiment, the transition between the two diameters 405 and 410 is demonstrated by a step 415.

The landing mandrel 400 is installed on the casing string 115. The casing head 300 inserts onto the landing mandrel 400. The outer profile of the landing mandrel 400 mates with the inner profile of the casing head 300 to position the landing mandrel 400 in such a way as to align the plurality of through holes 315 with the groove 420. Once the plurality of through holes 315 are aligned with the groove 420, a load-bearing pin 215 is inserted through each of the through holes 315 and into the groove 420. The number of load-bearing pins 215 and respective through holes 315 around the circumference of the casing head 300 and landing mandrel 400, are selected based on the expected load, and the tensile strength and shear strength of the load-bearing pins 215.

In certain embodiments, the interior side of the groove 420 includes a channel 425 on the top side. The channel 425 runs the entire circumference of the groove 420. Once a load-bearing pin 215 is fully inserted and rotated to the stopping point of the first flange 520, a second flange 525 that is oriented linearly with the first flange 520 enters the channel 425. In this embodiment, the first flange 520 functions as a locking mechanism. In this embodiment, the second flange 525 functions to prevent the load-bearing pin 215 from being removed from the groove 420. In embodiments where the quarter-circumferential channel 325 is located under the horizontal channel 320, the channel 425 would similarly be located at the bottom over the groove 420.

Although FIG. 4 illustrates one example of a landing mandrel 400, various changes may be made to FIG. 4. For example, the components of the landing mandrel 400 are for illustration only. Various components in FIG. 4 could be omitted, combined, or further subdivided and additional components could be added according to particular needs.

FIG. 5 illustrates a load-bearing pin 500 according to various embodiments of the present disclosure. The embodiment of the load-bearing pin 500 illustrated in FIG. 5 is for illustration only. In certain embodiments, the load-bearing pin 500 is one of the plurality of load-bearings pins 215 shown in FIG. 2. FIG. 5 does not limit the scope of this disclosure to any particular implementation of a wellhead assembly.

The load-bearing pin 500 includes a front portion 505, a middle portion 510, and a back portion 515. In certain embodiments, the load-bearing pin also includes a first flange 520, and a second flange 525. The front portion 505 of the load-bearing pin 500 enters the groove 420 of the landing mandrel 400. Once the front portion 505 of the load-bearing pin 500 enters the groove 420 of the landing mandrel 400, the middle portion 510 of the load-bearing pin 500 is located in the through hole 315 of the casing head 300. The back portion 515 of the load-bearing pin 500 remains outside the casing head 300.

Each of the front portion 505, middle portion 510, and/or back portion 515 of the load-bearing pins 500 can be partially threaded, fully threaded 530, or not threaded. In some embodiments, the middle portion 510 may only need a few threads 530 to mate with through hole 315 if through hole 315 is fully threaded. In another embodiment, the middle portion 510 is fully threaded and the through hole 315 is partially threaded. In another embodiment, the middle portion 510 is fully threaded and the through hole 315 is fully threaded.

In some embodiments, the front portion 505 of the load-bearing pin 500 is smooth 535 to facilitate insertion into the groove 420. In other embodiments, the entirety of the load-bearing pin 500 can be smooth and is held in place in the landing mandrel 400 and casing head 300 by different means, such as magnets or friction. In some embodiments, the back portion 515 of the load-bearing pin 500 can be a shape 540 to mate with a tool for rotating, such as a drill, a wrench, or a screwdriver.

In certain embodiments, the load-bearing pins 500 are permanently installed in the casing head 300. In these embodiments, the load-bearing pin 500 can include a wider front portion 505 and back portion 515 in order to not allow the load-bearing pin 500 to be removed. In this embodiment, the front portion 505 and the back portion 515 have a diameter greater than the diameter of the through hole 315.

In certain embodiments, the load-bearing pin 500 can be functionally in the extended state, such as by use of springs or magnets on the inside of the casing head 205 around the through hole 315. In this manner, the back portion 505 of load-bearing pins 500 are functional to pull the load-bearing pin 500 with a stopper to keep the front portion 505 retracted. In similar embodiments, the load-bearing pin 500 could include a tapered front portion 505. When the casing head 300 is inserted onto the landing mandrel 400, the tapered front portion 505 would interact with either the transition or step 415 between the second outer diameter 410 and the first outer diameter 405.

In certain embodiments, the load-bearing pin 500 may include a first flange 520 at the front portion 505 that acts as a locking mechanism when rotated in a channel 425 at the back end of the groove 420. In certain embodiments, the load-bearing pin 500 may also include a second flange 525 located in a middle portion 510 that extends into the horizontal channel 320 of the through hole 315. In some embodiments, the load-bearing pin 500 may include both a first flange 520 and a second flange 525. In embodiments wherein the load-bearing pin 500 includes both a first flange 520 and a second flange 525, when the load-bearing pin 500 is fully inserted the first flange is rotated in a channel 425 and the second flange 525 lines up with the quarter-circumferential channel 325 to orient the first flange 520 correctly with the groove channel 425.

Although FIG. 5 illustrates one example of a pin 500, various changes may be made to FIG. 5. For example, the components of the pin 500 are for illustration only. Various components in FIG. 5 could be omitted, combined, or further subdivided and additional components could be added according to particular needs.

FIG. 6 illustrates an example process 600 of assembling a wellhead assembly according to various embodiments of the present disclosure. For example, the process depicted in FIG. 6 could be performed using the combination of the casing head 300, the landing mandrel 400 and a plurality of load-bearing pins 500 illustrated in FIGS. 3-5.

In operation 605, the landing mandrel 400 is installed on a casing string 115 according to various embodiments of the disclosure.

In operation 610, the casing head 300 is positioned on the landing mandrel 400. The casing head 300 is structured to be positioned with through holes 315 of the casing head 300 aligned with a groove 420 of the landing mandrel 400. The outside profile of the landing mandrel 400 is structure with a first diameter 405 and a second outer diameter 410. The second diameter 410 is less than the first diameter 405 to correctly align the casing head 300 when placed onto the landing mandrel 400.

In operation 615, a plurality of load bearing pins 500 are engaged to secure the casing head 300 onto the landing mandrel 400. The type and amount of load bearing pins 500 are selected to not fail due to shear force cause by production of the oil or gas well. The load bearing pins 500 extend through the through holes 315 and into the grooves 420. In certain embodiments, once the load bearing pins 500 are in the grooves 420 they can be rotated so that a second flange 525 rotates in a quarter-circumferential channel 325 to align a first flange 520 with a channel 425 in the groove 420. In these embodiments, the first flange 520 inserted into the channel 425 keeps the load bearing pin 500 from being removed from the groove 420, essentially locking the load-bearing pin 500 in place.

In other embodiments, the load-bearing pins 500 may include a wider front portion 505 and back portion 515 in order to not allow the load-bearing pin 500 to be removed. In this embodiment, the front portion 505 and the back portion 515 have a diameter greater than the diameter of the through hole 315.

In other embodiments, the load-bearing pin 500 may be functionally in the extended state, such as by use of springs or magnets on the inside of the casing head 300 around the through hole 315. In this embodiment, the back portion 505 of load-bearing pins 500 are functional to pull the load-bearing pin 500 with a stopper to keep the front portion 505 retracted.

Although FIG. 6 illustrates and example process of assembling a wellhead assembly, various changes could be made to FIG. 6. For example, while show as a series of steps, various steps in each figure could overlap, occur in parallel, occur in a different order, or occur multiple times.

FIG. 7 illustrates an example process 700 of disassembling a wellhead assembly according to various embodiments of the present disclosure. For example, the process depicted in FIG. 6 could be performed on various embodiments of the wellhead assembly 200 illustrated in FIG. 200, or a combination of the casing head 300, the landing mandrel 400 and a plurality of load-bearing pins 500 illustrated in FIGS. 3-5. Certain embodiments may not be configured for the disassembly process 700 depicted in FIG. 7, for example embodiments where the load-bearing pins 500 include a wider front portion 505 and back portion 515 in order to not allow the load-bearing pin 500 to be removed.

In Operation 705, the plurality of load-bearing pins 500 are removed from the landing mandrel 400. In certain embodiments, springs or magnets on the inside of the casing head 205 around the through hole 315 may be removed, withdrawing the load-bearing pin 500 from its extended state. In another embodiment, the back end 515 of the load-bearing pin 500 may be reversibly rotated with a tool for rotating, such as a drill, a wrench, or a screwdriver, using the threads 530 of the load-bearing pin 500 to remove the load-bearing pin 500 from the through hole 315.

In Operation 710, the casing head 300 is removed from the landing mandrel 400 according to various embodiments of the present disclosure. The structure of the outside of the landing mandrel 400, which includes a first diameter 405 and a second outer diameter 410, allows the casing head 205 to be removed from the landing mandrel 400 when the plurality of load-bearing pins 500 are not inserted in the groove 420 through the through holes 315.

In Operation 715, the landing mandrel 400 is removed from the casing string 115 according to various embodiments of the present disclosure.

Although FIG. 7 illustrates and example process of assembling a wellhead assembly, various changes could be made to FIG. 7. For example, while show as a series of steps, various steps in each figure could overlap, occur in parallel, occur in a different order, or occur multiple times.

The description in this patent document should not be read as implying that any particular element, step, or function is an essential or critical element that must be included in the claim scope. Also, none of the claims is intended to invoke 35 U.S.C. § 112(f) with respect to any of the appended claims or claim elements unless the exact words “means for” or “step for” are explicitly used in the particular claim, followed by a participle phrase identifying a function. Use of terms such as (but not limited to) “mechanism,” “module,” “device,” “unit,” “component,” “element,” “member,” “apparatus,” “machine,” “system,” “processor,” “processing device,” or “controller” within a claim is understood and intended to refer to structures known to those skilled in the relevant art, as further modified or enhanced by the features of the claims themselves, and is not intended to invoke 35 U.S.C. § 112(f).

It may be advantageous to set forth definitions of certain words and phrases used throughout this patent document. The terms “application” and “program” refer to one or more computer programs, software components, sets of instructions, procedures, functions, objects, classes, instances, related data, or a portion thereof adapted for implementation in a suitable computer code (including source code, object code, or executable code). The terms “include” and “comprise,” as well as derivatives thereof, mean inclusion without limitation. The term “or” is inclusive, meaning and/or. The phrase “associated with,” as well as derivatives thereof, may mean to include, be included within, interconnect with, contain, be contained within, connect to or with, couple to or with, be communicable with, cooperate with, interleave, juxtapose, be proximate to, be bound to or with, have, have a property of, have a relationship to or with, or the like. The phrase “at least one of,” when used with a list of items, means that different combinations of one or more of the listed items may be used, and only one item in the list may be needed. For example, “at least one of: A, B, and C” or “at least one of: A, B, or C” includes any of the following combinations: A (alone); B (alone); and C (alone); A and B; A and C; B and C; and all three of A, B, and C.

While this disclosure has described certain embodiments and generally associated methods, alterations and permutations of these embodiments and methods will be apparent to those skilled in the art. Accordingly, the above description of example embodiments does not define or constrain this disclosure. Other changes, substitutions, and alterations are also possible without departing from the spirit and scope of this disclosure, as defined by the following claims. 

What is claimed is:
 1. A wellhead assembly, comprising: a casing head coupled to a casing string; a mandrel inserted into the casing head; and a plurality of load-bearing pins configured to secure the casing head onto the mandrel.
 2. The wellhead assembly of claim 1, wherein the casing head and the mandrel create a shear force on each of the plurality of load-bearing pins.
 3. The wellhead assembly of claim 1, wherein the plurality of load-bearing pins are inserted at a downward angle.
 4. The wellhead assembly of claim 1, wherein: a first load-bearing pin is inserted perpendicular to a fluid flow; and a second load-bearing pin is inserted at a downward angle.
 5. The wellhead assembly of claim 1, wherein each of the load-bearing pins includes a notch to orient the load-bearing pins.
 6. The wellhead assembly of claim 1, wherein: the casing head includes a plurality of through holes, the mandrel includes a groove that aligns with the plurality of through holes, and each of the load-bearing pins is inserted through a through hole into the groove.
 7. The wellhead assembly of claim 6, wherein the load-bearing pins are inserted into the groove to secure the mandrel once a production fluid is producing.
 8. A system, comprising: a casing string; and a wellhead assembly, the wellhead assembly further comprising: a casing head coupled to the casing string; a mandrel inserted into the casing head; and a plurality of load-bearing pins configured to secure the casing head onto the mandrel.
 9. The system of claim 8, wherein the casing head and the mandrel create a shear force on each of the plurality of load-bearing pins.
 10. The system of claim 8, wherein the plurality of load-bearing pins are inserted at a downward angle.
 11. The system of claim 8, wherein: a first load-bearing pin is inserted perpendicular to a fluid flow, and a second load-bearing pin is inserted at a downward angle.
 12. The system of claim 8, wherein each of the load-bearing pins includes a notch to orient the load-bearing pins.
 13. The system of claim 8, wherein: the casing head includes a plurality of through holes, the mandrel includes a groove that aligns with the plurality of through holes, and each of the load-bearing pins is inserted through a through hole into the groove.
 14. The system of claim 13, wherein the load-bearing pins are inserted into the groove to secure the mandrel once a production fluid is producing.
 15. A method of assembling a wellhead, comprising: coupling a casing head to a casing string; inserting a mandrel into the casing head; and securing the casing head onto the mandrel via a plurality of load-bearing pins.
 16. The method of claim 15, wherein the casing head and the mandrel create a shear force on each of the plurality of load-bearing pins.
 17. The method of claim 15, wherein the plurality of load-bearing pins are inserted at a downward angle.
 18. The method of claim 15, wherein: a first load-bearing pin is inserted perpendicular to a fluid flow, and a second load-bearing pin is inserted at a downward angle.
 19. The method of claim 15, wherein: the casing head includes a plurality of through holes, the mandrel includes a groove that aligns with the plurality of through holes, and each of the load-bearing pins is inserted through a through hole into the groove.
 20. The method of claim 19, wherein the load-bearing pins are inserted into the groove to secure the mandrel once a production fluid is producing. 